1. Field
The following description relates to preamble signal processing technology, and more particularly, to a preamble transmission device of a multi-mode supporting base station and a preamble detecting device of a multi-mode supporting user terminal.
2. Description of the Related Art
Technology associated with preamble processing was proposed in, for example, Korean Patent No. 10-1017970 (Feb. 21, 2011). Korean Patent No. 10-1017970 includes defining an inherent index for each frequency allocation (FA), allocating a preamble pseudo noise (PN) index to base stations using a reference FA index, defining an inherent offset by each FA for remaining FA indexes, shifting the preamble PN index allocated to the base stations using the reference FA index by the defined offset, and allocating the preamble PN index to base stations using the remaining FA indexes.
Recently, many studies and applications about a structure of a dual function-distributed base station in which a radio unit (RU) to handle a radio frequency (RF) function and a digital unit (DU) to handle a baseband and protocol functions are spatially separated are under development.
The function-distributed base station structure has an advantage in that processes for multi-modes are centrally handled in the DU, a concept of a cloud base station to share resources is introduced, and thereby utilizations and yields of the resources are maximized by cooperative communication between base stations.
The multi-mode supporting cloud base station may independently transmit preamble signals for each mode in one cell. However, a single-mode user terminal detects only the preamble signal adequate for its mode, automatically controls a size of receiving signals, performs synchronization procedures, and processes calls.
Therefore, conventional systems are implemented assuming an environment in which the base station supports multi-modes, but the user terminal supports only a single-mode, and therefore the base station manages radio resources.
Under this environment, the base station centrally manages the radio resources, but it is difficult to effectively select the mode according to a radio resource usage rate when there is a terminal that can support multi-modes using the conventional systems.
Accordingly, the inventors studied preamble processing technology for selecting the preamble signals by effectively selecting the mode according to the radio resource usage rate in a user terminal capable of supporting multi-modes, which contributes to smooth services from a user's viewpoint, and to effective use of the limited radio resources from an operator's viewpoint.